Squid 3.5.x < 3.5.18 Multiple Vulnerabilities

medium Nessus Network Monitor Plugin ID 9776
New! Plugin Severity Now Using CVSS v3

The calculated severity for Plugins has been updated to use CVSS v3 by default. Plugins that do not have a CVSS v3 score will fall back to CVSS v2 for calculating severity. Severity display preferences can be toggled in the settings dropdown.


The remote proxy server is affected by multiple attack vectors.


Versions of Squid 3.5.x prior to 3.5.18 are affected by multiple vulnerabilities :

- A flaw is triggered as input is not properly validated when handling HTTP request messages. This may allow a remote attacker to conduct a cache poisoning attack.
- A flaw is triggered as input is not properly sanitized when handling specially crafted host headers. This may allow a remote attacker to bypass same-origin protection mechanisms and cause the program to contact the wrong origin server. This may also poison downstream caches.
- Flaws in pointer handling and reference counting are triggered when handling specially crafted ESI response syntax. This may allow a remote server to cause a denial of service for Squid clients.


Either upgrade to Squid version 3.5.18 or later, or apply the vendor-supplied patch.

See Also


Plugin Details

Severity: Medium

ID: 9776

Family: Web Servers

Published: 11/11/2016

Updated: 3/6/2019

Dependencies: 3389

Risk Information


Risk Factor: Medium

Base Score: 5

Temporal Score: 4.4

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P

Temporal Vector: CVSS2#E:ND/RL:OF/RC:C


Risk Factor: Medium

Base Score: 5.3

Temporal Score: 5.1

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Temporal Vector: CVSS:3.0/E:X/RL:O/RC:C

Vulnerability Information

CPE: cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*

Patch Publication Date: 5/6/2016

Vulnerability Publication Date: 5/6/2016

Reference Information

CVE: CVE-2016-4553, CVE-2016-4554, CVE-2016-4555, CVE-2016-4556